Technical Field

[0001] The invention relates to a method for manufacturing an energy recovery arrangement and to a method for manufacturing a part of a vehicle implementing such method.

[0002] More particularly, the invention relates to a method for manufacturing an energy recovery arrangement for producing electric power from heat. Background Art

[0003] Thermoelectric generators, also known as TEGs, are known for producing electric power from heat.

[0004] There exists however a need to improve efficiency of electric power recovery by means of TEGs.

[0005] The invention aims at meeting such need.

Disclosure of invention

[0006] To this end, according to a first aspect, the invention proposes a method for manufacturing an energy recovery arrangement for producing electric power from heat, the energy recovery arrangement comprising a recovery wall having a thickness between opposite surfaces, and at least one thermoelectric generator arranged within the thickness of the recovery wall, the thermoelectric generator presenting a base and a height measured from the base, the method comprising:

- a step of forming by additive manufacturing process at least one primary wall portion of the recovery wall, the primary wall portion having at least one flat presenting a plane support surface within the thickness of the recovery wall,

- a step of forming a wedging structure on the support surface of the flat, the wedging structure defining at least one location on the support surface configured to receive the thermoelectric generator, the wedging structure having a height at least equal to the height of the thermoelectric generator,

- a step of placing the thermoelectric generator at the location, the base of the thermoelectric generator resting on the support surface, - a step of forming by additive manufacturing process at least one secondary wall portion of the recovery wall on the primary wall portion, on the wedging structure and on the thermoelectric generator,

wherein the primary and secondary wall portions and the wedging structure form together the recovery wall, and

wherein at least one of the primary and secondary wall portions intended to be exposed to heat is made of a thermally conductive material.

[0007] Thanks to these provisions, the thermoelectric generator may be integrated to the recovery wall in close proximity to the heat source, thereby enhancing efficiency of electric power recovery by means of the thermoelectric generator. In addition to the placement of the thermoelectric generator in any suitable location, the recovery wall may be shaped in any suitable manner thereby providing a high level of modularity to the energy recovery arrangement.

[0008] The wedging structure may present at least an abutment surface arranged to contact the thermoelectric generator,

the step of placing the thermoelectric generator at the location may include placing the thermoelectric generator in contact with the abutment surface of the wedging structure.

[0009] The wedging structure may comprise at least one wedging wall delimiting the location, the wedging wall being configured to surround at least partly the thermoelectric generator,

the step of forming the wedging structure may include forming by additive manufacturing process the wedging wall over the support surface.

[0010] The wedging wall may include at least a portion of the abutment surface.

[0011] The step of forming the wedging structure may include providing the wedging wall with at least one space and accommodating a separate wedging element in the space, the separate wedging element being preferably made of thermally insulating material.

[0012] The wedging wall may comprise at least two wedging wall portions having a height equal to the height of the thermoelectric generator and arranged next to each other with respect to a peripheral direction, the wedging wall portions presenting transverse surfaces perpendicular to the support surface and arranged next to each other with respect to the peripheral direction, one of said at least one space being delimited by the transverse surfaces.

[0013] The wedging wall may comprise at least one base having a height equal to a portion of the height of the thermoelectric generator, the base presenting a top surface parallel to the support surface, one of said at least one space being delimited by top surface.

[0014] The wedging wall may present a lateral surface perpendicular to the support surface and arranged to face the thermoelectric generator at a distance from the thermoelectric generator, one of said at least one space being delimited by the lateral surface.

[0015] One of said at least one space may be formed within the wedging wall.

[0016] The step of forming the wedging structure may include providing the wedging structure with a thermally insulating configuration.

[0017] The thermally insulating configuration may comprise a latticed configuration of at least a portion of the wedging structure.

[0018] The thermally insulating configuration may comprise at least one element made of thermally insulating material integrated in the wedging structure.

[0019] The thermoelectric generator may comprise an electric generation portion and a harness for conducting the electric power, and the wedging structure may present at least one guiding surface configured to guide the harness along the support surface.

[0020] The additive manufacturing process may be a selective laser melting process in which layers of powder material are spread successively, selective portions of powder material of each layer corresponding to portions of the recovery energy arrangement formed by the selective laser melting process being melted by a laser beam, at least one of the primary and secondary wall portions and the wedging structure being provided with passages to remove powder in excess.

[0021] During at least one of the steps of forming the primary and secondary wall portions, at least one of the surfaces of the recovery wall may be shaped to enhance heat exchange with surroundings of the recovery wall. [0022] According to a second aspect, the invention proposes a method for manufacturing a part of a vehicle exposed to heat comprising implementing the method for manufacturing as defined previously to form an energy recovery arrangement as a portion of the part of the vehicle. Brief Description of Drawings

Other objects and advantages of the invention will emerge from the following disclosure of particular embodiments of the invention given as non-limitative examples, the disclosure being made with reference to the enclosed drawings in which:

- figure 1 is a representation of a part of an internal combustion engine of a vehicle, illustrating a combustion chamber delimited by a cylinder and a piston reciprocating within the cylinder, and an exhaust circuit for exhausting gases burnt in the combustion chamber, a wall of the internal combustion engine and a portion of the exhaust circuit forming energy recovery arrangements for producing electric power from heat,

- figure 2 is a representation in section along the orientation referenced ll-ll on figure 1 of the portion of the exhaust circuit forming one of the energy recovery arrangements, the portion of the exhaust circuit having a recovery wall and thermoelectric generators arranged within a thickness of the recovery wall,

- figure 3 is a representation in section along the orientation referenced Ill-Ill on figure 1 of a wall of the internal combustion engine forming one of the energy recovery arrangements, the portion of the combustion chamber having a recovery wall and thermoelectric generators arranged within a thickness of the recovery wall,

- figure 4 is a flowchart illustrating a method for manufacturing the energy recovery arrangements according to the invention,

- figures 5 and 6 are representations respectively from top and in elevation of steps of the method for manufacturing the energy recovery arrangements according to a first embodiment of the invention, the steps consisting in forming by additive manufacturing process a primary wall portion of the recovery wall, and forming a wedging structure defining locations configured to receive the thermoelectric generators, the wedging structure presenting abutment surfaces arranged to contact the thermoelectric generators, the wedging structure according to the first embodiment comprising wedging walls formed by additive manufacturing process and including the abutment surfaces,

- figures 7 and 8 are representations respectively from top and in elevation of a further step of the method for manufacturing the energy recovery arrangements, the step consisting in placing the thermoelectric generators at the locations, - figure 9 is a representation in elevation of a subsequent step of the method for manufacturing the energy recovery arrangements, the step consisting in forming by additive manufacturing process a secondary wall portion forming the recovery wall together with the primary wall portion and the wedging structure,

- figure 10 is a representation from top of the step of forming the wedging structure of the method of manufacturing according to a second embodiment of the invention, wherein the wedging walls are provided with spaces and the wedging structure comprises separate wedging elements accommodated in the spaces, the wedging wall comprising wedging wall portions defining spaces between them in which the wedging elements are arranged, the wedging elements including portions of the abutment surfaces,

- figure 11 is an enlarged view in perspective of the detail referenced XI on figure 10, illustrating one of the wedging elements arranged within one of the spaces between wedging wall portions of the wedging wall,

- figure 12 is an enlarged views in perspective of alternatives of the detail referenced XII on figure 10, illustrating latticed configurations of a portion of the wedging wall as thermally insulating configuration,

- figures 13, 14 and 15 are representations in elevation of the steps of the method for manufacturing according to a first alternative of the second embodiment of the invention, wedging walls presenting lateral surfaces perpendicular to the support surface and arranged to face the thermoelectric generators at a distance from the thermoelectric generators, the separate wedging elements including the abutment surfaces being arranged within spaces delimited by the lateral surfaces,

- figures 16, 17 and 18 are representations in elevation of the steps of the method for manufacturing according to a second alternative of the second embodiment of the invention, the wedging walls presenting bases as abutment portions, and remaining portions, the abutment portions including portions of the abutment surfaces and the remaining portions including lateral surfaces spaced apart from the abutment surfaces, the separate wedging elements including portions of the abutment surfaces being arranged within spaces delimited by the lateral surfaces of the remaining portions and top surfaces of the abutment portions,

- figure 19 is a representation in elevation of the step of forming the wedging structure of the method for manufacturing according to a third alternative of the second embodiment of the invention, the abutment potions of the wedging walls being arranged at a distance from the support surface,

- figure 20 is a representation in elevation of the step of forming the wedging structure of the method for manufacturing according to a fourth alternative of the second embodiment of the invention, spaces being formed within the wedging walls,

- figures 21 , 22 and 23 are representations in section along the orientation referenced ll-ll on figure 1 of the portion of the exhaust circuit, illustrating alternative arrangements of thermoelectric generators,

- figure 24 is a representation in section along the orientation referenced Ill-Ill on figure 1 of the wall of the internal combustion engine, illustrating an alternative arrangement of thermoelectric generators.

Description of Embodiments

[0023] In the Figures, the same reference numbers refer to the same or similar elements.

[0024] Figure 1 represents of a part of an internal combustion engine 1 of a vehicle. The internal combustion engine 1 comprises several combustion chambers 2 each delimited by a cylinder 3 and a piston 4 reciprocating within the cylinder 3. An injection circuit, not shown, supplies each combustion chamber 2 with the necessary mixture of fluid, including fuel and oxygen, that is burnt upon ignition as known from the operation cycle of the internal combustion engine 1. The burnt gases are exhausted from each combustion chamber 2 by an exhaust circuit 10 of which an exhaust duct 11 in communication with the combustion chamber 2 through an exhaust valve 15 is represented.

[0025] As shown on figure 2, illustrating a section of the exhaust duct 11 of the exhaust circuit 10, a portion of the exhaust duct 11 may include an energy recovery arrangement 20 for producing electric power from heat.

[0026] In particular, the exhaust duct 11 has a tubular wall 12 presenting opposite internal 12a and external 12b surfaces, cylindrical of generally circular cross- section about a central axis. A portion of the wall 12 of the exhaust duct 11 is configured as a recovery wall 21 having a thickness within which at least one thermoelectric generator 40, hereafter referred to as TEG, is arranged. On figure 2, three TEGs 40 are shown. The recovery wall 21 having integrated TEGs 40 may then recover heat from a heat source, the burnt gases in the present case, to transform it into electric power.

[0027] As it will become apparent from the following of the description, the TEGs 40 are arranged to produce electric power from heat recovered from the portion of the internal surface 12a of the exhaust duct 11 in contact with burnt gases circulating within the exhaust duct 11.

[0028] At least one of the surfaces of the recovery wall 21 may be shaped to enhance heat exchange with surroundings of the recovery wall 21. On figure 2, the portion of the external surface 12b of the exhaust duct 11 delimiting the recovery wall 21 is provided with protrusions 13 enhancing a cooling of the external surface 12b. The portion of the internal surface 12a of the exhaust duct 11 delimiting the recovery wall 21 could also be shaped in a similar manner to enhance heat transfer to the TEGs 40.

[0029] The energy recovery arrangement 20 is not limited to a tubular wall of a duct, especially of the exhaust duct 11. The energy recovery arrangement 20 may be formed in any wall of any suitable location close to a heat source of the internal combustion engine or of the vehicle or of any machine,.

[0030] For example, as shown on figure 3 a wall 6 of a casing 5 of the internal combustion engine 1 may include energy recovery arrangements 20 for producing electric power from heat. [0031] The wall 6 presents conduits 7 in at least some of which a hot fluid circulates. The wall 6 has internal surfaces 6a, that is cylindrical of circular cross section about a central axis, delimiting the conduits 7, and a generally plane external surface 6b opposite the internal surface 6a. A portion of the wall 6 is configured as a recovery wall 21 having a thickness within which at least one TEG 40 is arranged. On figure 3, two TEGs 40 in proximity of the internal surface 6a of each conduit 7 are shown. Here again, the recovery wall 21 having integrated TEGs 40 may recover heat from a heat source, the hot fluid in the present case, to transform it into electric power. [0032] In relation with figures 4 to 9, a method for manufacturing at least a portion of the exhaust duct 11 including its recovery wall 21 and at least a portion the casing 5 including its recovery wall 21 is disclosed.

[0033] Such method implements a method for manufacturing the energy recovery arrangement 20 as the above mentioned portions of the internal combustion engine 1 of the vehicle.

[0034] As shown on figure 4, the method for manufacturing the energy recovery arrangement 20 comprises the steps of:

- a step S1 of forming by additive manufacturing process at least one primary wall portion 21 a of the recovery wall 21 ,

- a step S2 of forming a wedging structure 25 defining locations configured to receive the TEGs 40,

- a step S3 of placing the TEGs 40 at the locations,

- a step S4 of forming by additive manufacturing process at least one secondary wall portion 21 b of the recovery wall 21 on the primary wall portion 21a, on the wedging structure 25 and on the thermoelectric generator 40.

[0035] Details as to the steps of the method for manufacturing the energy recovery arrangement 20 are given in relation with Figures 5 to 9.

[0036] At step S1 , the primary wall portion 21 a is formed with at least one flat presenting a plane support surface 22. The flat is arranged so as to be located within the thickness of the recovery wall 21. The support surface 22 is intended to support the TEGs 40. In the case of the exhaust duct 11 , the primary wall portion 21 a may include an essential portion of the wall 12 of the exhaust duct 11 , including the internal surface 12a. In the case of each conduit 7, the primary wall portion 21a may include a bottom portion of the casing 5 of the internal combustion engine 1.

[0037] The primary wall portion 21 a of each recovery wall 21 is formed by additive manufacturing process.

[0038] In particular, the additive manufacturing process may be a selective laser melting process. In such additive manufacturing process, layers of powder material are spread successively and selective portions of powder material of each layer corresponding to portions of the recovery wall 21 to be are melted by a laser beam.

[0039] Figures 5 and 6 are respectively a top view and a view in elevation, namely a side view, of the step S2 of forming a wedging structure 25.

[0040] The wedging structure 25 is formed on the support surface 22 of the flat of the primary wall portion 21a and includes one or several wedging members 26 each arranged around a central axis A perpendicular to the support surface 22 to surround at least partly one of the TEGs 40.

[0041] Preferably, each wedging member 26 of the wedging structure 25 presents an abutment surface 27 arranged to contact the TEGs 40. In doing so, the TEGs 40 may be precisely located on the support surface 22 and correctly wedged to avoid subsequent movement and deterioration. Also heat transfers may be better controlled and optimized and rigidity of the energy recovery arrangement 20 can be ensured.

[0042] As apparent from figure 5, each wedging member 26 may be discontinuous in a peripheral direction around the central axis A to provide the wedging structure 25 with passages 28 to remove powder in excess resulting from the selective laser melting process, and with one or several guiding surfaces 29 or one or several spaces 31 of which utility will become apparent from the following of the description.

[0043] Each wedging member 26 of the wedging structure 25 has a height, measured perpendicularly from the support surface 22, at least equal to a height of the TEG 40.

[0044] According to a first embodiment shown on figures 5 and 6, each wedging member 26 comprises a wedging wall 30 formed by additive manufacturing process, preferably the selective laser melting process, over the support surface 22 to delimit the location for the TEG 40. In the first embodiment, each wedging member 26 is only made of the wedging wall 30 which includes the abutment surface 27 and which has a height, measured perpendicularly from the support surface 22, equal to a height of the TEG 40.

[0045] Figures 7 and 8 are respectively a top view and a view in elevation, namely a side view, of the subsequent step S3 of the method for manufacturing the energy recovery arrangements which consists in placing the TEGs 40 at the locations defined by the wedging walls 30, in contact with the abutment surfaces 27.

[0046] More particularly, each TEG 40 comprises an electric generation portion 41 for generating electric power from heat and a harness 45, for example including wires, for conducting the electric power generated by the electric generation portion 41. Examples of suitable TEGs are known from CN 105149576, WO 2013/144107 or DE 10 2012 208 295.

[0047] The electric generation portion 41 has a base 42 from which the height of the TEG 40 is measured. Each TEG 40 is placed at one of the location of the wedging structure 25 with its base 42 resting on the support surface 22 and a lateral surface 43 in contact with the abutment surface 27, the harness 45 running along the support surface through the passage 28 while being guided by the guiding surfaces 29. A top surface 44 of the TEG 40, opposite the base 41 , is flush with the wedging structure 25.

[0048] Optionally, before proceeding with the subsequent step of the method for manufacturing the energy recovery arrangement which consists in forming by additive manufacturing process the secondary wall portion 21 b, the wedging structure 25 may be completed by one or several protective members covering at least the TEGs and possibly the wedging members 26. In such case, the wedging structure 25 has a height superior to that of the TEGs.

[0049] Figure 9 illustrates the step S4 of forming by additive manufacturing process the secondary wall portion 21 b with forms the recovery wall 21 together with the primary wall portion 21 a and the wedging structure 25.

[0050] At this step S4, in the above disclosed case related to the exhaust duct 11 , the external surface of the recovery wall 21 is shaped with the protrusions 13.

[0051] To enable heat exchange with the heat source, at least one of the primary 21 a and secondary 21 b wall portions intended to be exposed to heat is made of a thermally conductive material. Possibly, the wedging structure 25 is also made at least in part of a thermally conductive material.

[0052] In the above disclosed case related to the exhaust duct 11 , at least the primary wall portions 21a of the recovery wall 21 is made of thermally conductive material. In the above disclosed case related to the conduits 7, at least portions of the primary 21 a and secondary 21 b wall portions of the recovery wall 21 including the internal surface 6a of the casing 5 are made of thermally conductive material.

[0053] According to a second embodiment of the invention, in addition to wedging walls 30 formed by additive manufacturing process, the wedging member 26 of the wedging structure 25 may comprise one or several separate wedging elements 35. The wedging wall 30 of the wedging member 26 may then be provided with spaces 31 in which the wedging elements 50 can be accommodated.

[0054] According to particular provisions, although not limited thereto, the wedging element 35 may be an element made of thermally insulating material integrated in the wedging structure so as to provide the wedging structure with thermally insulating configuration.

[0055] On figures 10 and 11 , the wedging wall 30 is provided with spaces 31 each arranged between two wedging wall portions 32 of the wedging wall 30. Each pair of wedging wall portions 32, formed by additive manufacturing process, extend perpendicularly from the support surface 22 and have a height equal to the height of the TEG 40. The wedging wall portions 32 are arranged next to each other with respect to the peripheral direction around the central axis A. The wedging wall portions 32 present respective transverse surfaces 30a perpendicular to the support surface 22 and arranged next to each other with respect to the peripheral direction. The space 31 is delimited by the transverse surfaces 30a.

[0056] The wedging element 35 accommodated within the space 31 includes portions of the abutment surface 27, other portions of the abutment surface 27 being formed on the wedging wall 30.

[0057] As shown on figure 12, in an alternative or complementary manner, the thermally insulating configuration of the wedging structure could be provided by one or several latticed configurations of a portion of the wedging wall 30.

[0058] In a first alternative represented on figures 13, 14 and 15, the wedging wall 30 presents a lateral surface 30b perpendicular to the support surface and arranged to face the TEG 40 at a distance from the TEG 40. At the step of forming the wedging structure 25, once the wedging wall 30 is formed by the additive manufacturing process, the wedging member 26 is completed with the wedging elements 35 arranged within spaces 31 delimited by the lateral surface 30b.

[0059] In such case, the wedging elements 35 include the abutment surfaces 27.

[0060] In a first alternative represented on figures 16, 17 and 18, the wedging wall 30 present a base configured as an abutment portion 33 having portions of the abutment surface 27. The abutment portion 33 extends from the support surface 22 up to a top surface 33a parallel to the support surface 22 and arranged at a height equal to a portion of the height of the TEG 40. The wedging wall 30 also has a remaining portion 34 formed on the abutment portion 33 and including the lateral surface 30b spaced apart from the abutment surface 27. The separate wedging elements 35, including portions of the abutment surface 27 complementary to that of the abutment portions 33, are arranged within spaces 31 delimited by the lateral surfaces 30b of the remaining portions 34 and the top surfaces 33a of the abutment portions 33.

[0061] As shown on figure 19, according to a third alternative, the abutment potion 33 of the wedging wall 30 having portions of the abutment surface 27 protruding from the lateral surface 30b of the remaining portion 34 can be arranged at a distance from the support surface 22. Spaces 31 adapted to accommodate wedging elements can be formed above and under the abutment potion 33.

[0062] In a fourth alternative shown on figure 20, the wedging walls 30 can be formed with internal spaces 31 formed between opposite abutment surfaces 27.

[0063] In other embodiments, wedging structure 25 may be deprived of any wedging wall 30 formed by additive manufacturing process. Only separate wedging elements 35 could then be placed on the support surface 22.

[0064] The invention enables a high modularity in the manufacturing of the energy recovery arrangement, including the placement of the TEGs in accordance with the required need. For example, in figure 21 , the external surface of the exhaust duct 11 at the recovery wall is deprived from protrusions 13. In figure 22, the TEGs 40 are arranged farther from the internal surface of the wall of the exhaust duct 11. In figure 23, a higher number of TEGs is arranged within the thickness of the recovery wall 21 of the exhaust duct 11. Similarly, in figure 24, a higher number of TEGs is arranged within the thickness of the recovery wall 21 of the casing 5.

[0065] The invention has been disclosed in relation with of parts of an internal combustion engine of a vehicle configured as energy recovery arrangements. The invention is however not limited to such parts of an internal combustion engine and could apply to any other relevant part of a vehicle and more generally to any other part of a machine or other arranged in close proximity of a heat source.